Art that separately measures the operating state of electrical devices, including inverters, used in the home and the like, that, rather than installing measuring instruments in each electrical device, non-invasively estimates the operating state of each electrical device, based on a measurement on the lead-in power line from a utility pole to the home has been proposed.
When estimating the operating state of each electrical device, if a plurality of home appliances is simultaneously operating, the number of combinations in the estimation becomes extremely large, and the amount of operation time and amount of memory capacity used in the operation processing might increase. Additionally, because the number of combinations in the operation processing becomes extremely large, erroneous detection might more frequently occur.